Electric axle assembly

ABSTRACT

An electric axle assembly having dual motors and dual disconnects allowing for selectably disconnecting either one of the motors so that either motor may operate as the primary drive motor. Each of the dual motors is coupled to a layshaft, and each disconnect is positioned between a gear reduction at the output of the motor and a gear reduction connected to the layshaft. The layshaft is coupled to a differential via a clutch and gear set, the gear set providing a two-speed transmission for power delivered from the layshaft to the differential.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 62/832,367, entitled “Electric Axle Assembly,” and filed on Apr. 11,2019, the entire contents of which is hereby incorporated by referencefor all purposes.

FIELD

The invention relates to an electric axle assembly, and moreparticularly, to an electric axle assembly having dual electric motorgenerators.

BACKGROUND AND SUMMARY

Electric vehicles (EVs) typically use an electric motor as its primarydrive motor or source of propulsion. The electric motor convertselectrical energy (electrical power usually expressed in kilowatts (kW))into power to rotate the vehicle wheels. The electric motor may alsooperate as a generator to convert rotation of the wheels into electricalenergy. Thus, as well understood, the electric motor may sometimes bereferred to as an electric motor, or a power supply, or an electricgenerator, or an electric motor generator. The electric motor can be ofdifferent types, with AC motors being the most common. Vehicle batteriesstore the electricity required to run the EV, with the capacity (range)of the batteries usually expressed in kWh (kilowatt-hours). An inverterconverts electric direct current (DC) from the batteries intoalternating current (AC) used by the AC motor to spin a rotor of themotor, the rotor linked to other parts of the vehicle drivetrain to sendpower to the wheels. EVs may use a single-speed transmission or asingle-speed gear set to supply power to the wheels, usually through adifferential interconnected with half-shafts, or other axle componentsextending to each wheel. However, other EV designs incorporate amulti-speed transmission in order to improve operating characteristicsat various vehicle speeds and conditions. Still other EV designs mayincorporate more than one electric motor.

For example, dual electric motors may be used. In some applicationsusing dual electric motors, one motor may be optimized for power and theother may be optimized for range. Dual motors may, for example, be usedfor redundancy, so that the vehicle may operate if one of the motorsbecome inoperative or damaged. When an electric vehicle includes twoelectric motor generators it is typical that one of the electric motorgenerators acts as a primary source of propulsion. Having one electricmotor generator act as the primary source of propulsion causes theprimary electric motor generator to wear more quickly than the secondelectric motor generator. It would be desirable, therefore, to be ableto select which electric motor generator acts as the primary source ofpropulsion in order to distribute wear to evenly to the electric motorgenerators in an electric axle.

Further, an electric axle assembly having a multi-speed transmission,such as for example a two-speed transmission, and/or a dual motorconfiguration, has increased component complexity, increased spacerequirements for packaging the components within the vehicle system, andincreased weight due to the additional number of components. Weightdistribution of the electric axle assembly within the vehicle system isanother factor, where a lower center of mass within the vehicle and/orparticular distributions fore and aft or in relation to opposite wheelsof the vehicle may be of additional importance for improved vehicleoperating performance.

To address at least some of the aforementioned and other problems,embodiments for an electric axle assembly are provided. According to afirst aspect of the disclosure is an electric axle assembly comprising afirst motor generator having a first disconnect mechanism disposedbetween a first gear reduction at the output of the first motorgenerator and a second gear reduction connected to a layshaft, thelayshaft operably coupled to a differential via a clutch assembly, theclutch assembly disposed on the layshaft and engaged with a gearassembly, with the gear assembly being operatively connected to thedifferential, and a second motor generator having a third gear reductionat the output of the second motor generator and a fourth gear reductionconnected to the layshaft, wherein the first disconnect mechanism isadapted to permit the first motor generator to be selectably operablydisconnected from the layshaft while the second motor generator remainsoperably connected to the layshaft.

In one aspect, the electric axle assembly further comprises a seconddisconnect mechanism disposed between the third gear reduction at theoutput of the second motor generator and the fourth gear reductionconnected to the layshaft, wherein the second disconnect mechanism isadapted to permit the second motor generator to be selectably operablydisconnected from the layshaft.

In one aspect, the first disconnect mechanism is communicably coupled toa controller, and the controller is adapted to selectably disconnect thefirst motor generator via the first disconnect mechanism when less thana predetermined level of power is required by the vehicle.

In one aspect, the first disconnect and the second disconnect areadapted to permit engaging either one of the first motor generator orthe second motor generator as a primary drive motor based on a time atload for the first motor generator and a time at load for the secondmotor generator.

In one aspect, the first disconnect and the second disconnect areadapted to permit alternating between the first motor generator and thesecond motor generator as primary drive motors during operation of thevehicle to extend the life of each driving motor.

In one aspect, the first disconnect and the second disconnect areadapted to permit engaging both the first motor generator and the secondmotor generator at the same time so that both the first motor generatorand the second motor generator provide power to the differential for apredetermined duration, after which a controller selectably operablydisconnects either the first motor generator or the second motorgenerator from the layshaft, with selection as to which motor generatorto disconnect based on algorithms used by the controller.

In one aspect, the first disconnect and the second disconnect areadapted to permit spinning up an operably disconnected motor generatorto operably match a rotational speed of the layshaft so as to operablyreconnect the formerly disconnected motor generator.

In one aspect, the first gear reduction includes a first gear thatrotates with an output shaft of the first motor generator and a secondgear that rotates with a first intermediate shaft, the second gearreduction includes a third gear that rotates with the first intermediateshaft and a fourth gear that rotates with the layshaft, the third gearreduction includes a seventh gear that rotates with a secondintermediate shaft and the fourth gear that rotates with the layshaft,and the fourth gear reduction that includes a fifth gear that rotateswith an output shaft of the second motor generator and a sixth gear thatrotates with the second intermediate shaft.

In one aspect, the clutch assembly disposed on the layshaft andoperatively connected to the differential is adapted to permit operationof the electric axle assembly at one of two different rotational speeds.

In one aspect, an output shaft of the first motor generator, thelayshaft, and an output shaft of the second motor generator are in aparallel alignment with one another, the output shaft of the secondmotor generator is hollow, and at least a portion of an axle shaftoperatively coupled to the differential extends through the hollowoutput shaft of the second motor generator.

In another aspect, an electric axle assembly in a vehicle comprises: afirst motor generator; a first motor shaft operatively coupled to thefirst motor generator; a first gear reduction connected to the motorshaft; a first intermediate shaft connected to the first gear reduction;a first disconnect mechanism provided in the first intermediate shaft toselectively disconnect a first portion and a second portion of the firstintermediate shaft; a second gear reduction connected to the firstintermediate shaft; a second motor generator; a second motor shaftoperatively coupled to the second motor generator; a third gearreduction connected to the second motor shaft; a second intermediateshaft connected to the third gear reduction; a fourth gear reductionconnected to the second intermediate shaft; a layshaft connected to thesecond gear reduction and the fourth gear reduction; and a differentialoperatively connected to the layshaft.

In one aspect, the electric axle assembly further comprises a seconddisconnect mechanism provided in the second intermediate shaft toselectively disconnect a first portion and a second portion of thesecond intermediate shaft.

In one aspect, the electric axle assembly further comprises a clutchassembly disposed on the layshaft, the clutch assembly engaged with agear assembly and the gear assembly being operatively connected to thedifferential.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated herein as part of thespecification. The drawings described herein illustrate embodiments ofthe presently disclosed subject matter, and are illustrative of selectedprinciples and teachings of the present disclosure. However, thedrawings do not illustrate all possible implementations of the presentlydisclosed subject matter, and are not intended to limit the scope of thepresent disclosure in any way.

FIG. 1 is a schematic view of an electric axle assembly in accordancewith an embodiment.

FIG. 2 is a schematic view of an electric axle assembly in accordancewith another embodiment.

FIG. 3 is a perspective view illustrating portions of the electric axleassembly, according to embodiments.

Similar reference numerals may have been used in different figures todenote similar components. FIG. 3 is shown with components inproportional size with one another, according to some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the assemblies, devices, andmethods illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts. Hence, specific dimensions, directions, or otherphysical characteristics relating to the embodiments disclosed are notto be considered as limiting, unless expressly stated otherwise.

As an overview, FIG. 1 is a schematic of an electric axle assembly andsystem 100, according to some embodiments, comprising two electric drivemotors, with each motor connected to a common layshaft that is coupledto a differential; and in the system 100, the electric axle assembly 10includes a disconnect so that one of the two motors may be disengaged.Each of the motors are connected at their output to a gear reduction,and the layshaft common between the two motors includes, as shown, aclutch assembly having two gears. The gears provide two different gearcombinations (or speeds) for transmitting power from the layshaft to thedifferential. And the differential, as shown, is coupled with axleshafts (or half shafts) connectable to respective wheels. A controller102 is shown, for controlling the clutches and actuators associated withthe motor disconnect and/or layshaft clutch assembly.

FIG. 2 is a schematic of an electric axle assembly and system 200,according to some embodiments, comprising the same components as in FIG.1 except that two disconnects are provided, one for each of the twomotors.

FIG. 3 provides a perspective view of exemplary gears comprising theelectric axle assembly and systems 100, 200. FIG. 3 illustrates acompact, space-saving arrangement and layout of the gears, as well as anarrangement whereby the motor shafts, layshaft, and intermediate shaftsare substantially parallel to one another, and the gears aresubstantially perpendicular to the shafts and parallel (and closelyspaced) to one another. Also shown in FIG. 3 is the separation betweenmotor shafts 22 and 52, effectively providing separation (therebyproviding improved cooling/thermal management) between motors 24 and 50,respectively.

Generally, the present inventors discovered the described dual electricmotor disconnect embodiments for improving drive axle/electric axleassembly/system efficiency, motor and gear train/system cooling, andmotor life optimization. More specifically, system efficiency at highwayspeeds prompted the present inventors to develop various improvementssuch as the embodiments described herein, which provide fordisconnecting either one of two motors, in a compact layout (e.g.,taking less space with shafts in parallel and gears closely packed),favorably positioned/arranged (e.g., lower in height with respect to thevehicle drive axle due to the axle shaft extending through the hollowshaft 22 of the motor 24), higher performance (e.g., two speedtransmission and dual motors) and weight reduced (due to compactlayout/size) electric axle assembly. The embodiments described hereinfor an electric axle assembly having dual motors, allow for driving withone primary motor and allow the motor/vehicle controller to switchbetween primary motors to allow each motor to achieve the sametheoretical wear (damage) instead of having one motor operating at nearfull capacity, for example, 80% of the time.

In FIG. 1, the motor 50 is shown as having a disconnect 70 between thefirst gear reduction (or gear reduction 56, 58) and the second gearreduction (or gear reduction 66, 46) that ties into the layshaft 48. Themotor 50 would be (in intended operation) disconnected at modes ofoperation where less than 200 kW of power is required by the vehicle.Based on a duty cycle for the vehicle, less than approximately 20 to 30%of the operating time requires greater than 200 kW of power. Therefore,in typically anticipated operating conditions, the primary motor 24would be in operation 100% of the time, and the motor 50 would be inoperation only 20-30% of the time. By disconnecting the motor 50, motorwear (damage) is avoided and drag (due to the spinning mass) is reducedby idling the rotor and reduction gears connected to the output shaft ofthe idled motor.

In FIG. 2, a (second) disconnect 44 is shown between the first reductiongear (or gear reduction 30, 32) from the motor 24 and the secondreduction (gear reduction 42, 46) that ties into the layshaft 48. Byhaving disconnects (such as disconnects 44 and 70) attached to bothmotor positions, the primary motor may be selected based on time at load(for each separate motor) and may be used to alternate between primarymotors during operation to extend the life of each driving motor.

The present inventors discovered further advantages. For example, from a(vehicle) stop, it is likely that both motors will be engaged to allowthe vehicle to get up to speed more rapidly, and either motor may bedisconnected at that point based on algorithms in the controller, suchas controller 102. As the embodiments described further provide, anability to spin the electric motor up to speed (from idle to a targetRPM) with zero torque command allows speed matching to re-engage themotor if more power is needed without having to need a torque interruptas well. Operation in a zero torque mode allows the electric motor to befully fluxed and ready to begin rotation when a speed command or torquecommand is given. By having disconnects (such as disconnects 44 and 70)attached to both motor positions, either motor may be idled and thenefficiently brought back up to speed so as to re-engage with thelayshaft and thereby supply power to the (differential and) driveshafts/axle shafts (and wheels connectable thereto).

Embodiments of an electric axle assembly 10 are illustrated in FIGS.1-3. The electric axle assembly 10 may be utilized as an electric driveaxle. The electric axle assembly 10 may have applications in commercialvehicles, both light duty and heavy duty vehicles, and for passenger,off-highway, and sport utility vehicles. Additionally, the electric axleassembly 10 may be adapted for use in front and/or rear driving axles,and steerable and non-steerable axles. It is to be understood that theelectric axle assembly 10 may also have industrial, locomotive,military, agricultural, and aerospace applications. Moreover, variousinventive aspects described herein in the context of an electric axleassembly may separable.

In an embodiment, the electric axle assembly 10 is in mechanicalcommunication with a differential 12. In one embodiment, the electricaxle assembly 10 comprises the differential 12. The differential 12 maybe operatively attached to an axle 14. The axle 14 may comprise a firstaxle shaft 16 and a second axle shaft 18. Each axle shaft 16, 18 may beattached to a respective wheel 20.

The first axle shaft 16 preferably extends through a hollow motor shaft22. The hollow motor shaft 22 extends from and is operatively coupled toan electric motor generator 24. As illustrated in FIG. 1, the axle 14and the first electric motor generator 24 may be in a parallelconfiguration. As used herein, the phrase “parallel configuration” mayrefer to the parallel arrangement and orientation of the power outputshaft (motor shaft) 22 in relation to the axles (half shafts) 14, 18.

As shown in FIG. 3, the hollow motor shaft 22 is supported by bearings26. Preferably, the bearings supporting motor shaft 22 comprise a firstand a second bearing. A housing (not depicted) may surround at least aportion of the first electric motor generator and the hollow motorshaft. The housing may be constructed to further contain and circulate alubricant including, but not limited to, an oil.

The hollow motor shaft 22 may be operatively connected to a gear train28. The gear train 28 may be used to provide input to and output fromthe electric motor generator 24. The gear train 28 may comprise helicalgears (as illustrated in FIG. 3).

In an embodiment, the gear train 28 comprises a gear 30 operativelyattached to and rotating with the hollow motor shaft 22. The gear 30 anda gear 32 are engaged and rotate together. Preferably, the gear 30 andthe gear 32 provide a gear reduction (referred herein as “gear reduction30, 32”.

The gear 32 is operatively attached to and rotates with an intermediateshaft 34. In FIG. 1, the intermediate shaft 34 comprises a shaft 106 orconnecting member 106 or simply a fixed connected relationship 106between gear 32 and gear 42. Gear 32 and gear 42, as shown, arerotatably fixed to one another such that both gears 32 and 42 rotatetogether with one another at the same rate or RPM.

In the embodiment shown in FIG. 2, the first intermediate shaft 34preferably comprises a first portion 36 and a second portion 38. Thefirst portion 36 is attached to the gear 32 and supported for rotationby bearings 40, which are illustrated in FIG. 3. The first portion 36and the gear 32 rotate together. The second portion 38 is attached tothe gear 42. The second portion 38 and the gear 42 rotate together. Insome embodiments, the second portion 38 is supported for rotation bybearings (not depicted).

For the embodiment shown in FIG. 2, a disconnect mechanism 44 isprovided in the intermediate shaft 34 to selectively disconnect thefirst portion 36 and the second portion 38. When the disconnectmechanism 44 is activated (so as to disconnect the gear 32 from the gear42), the (rotational) power provided by the motor generator 24 is notcommunicated to the second portion 38 of the intermediate shaft 34. Whenthe disconnect mechanism 44 is not activated (so as to leave the gear 32connected to the gear 42), the power provided by the motor generator 24is communicated from the first portion 36 to the second portion 38 ofthe intermediate shaft 34.

The gear 42 is engaged and rotates with a gear 46. The gear 46 isoperatively attached to and rotates with a layshaft 48. Preferably, thegear 42 and the gear 46 provide a gear reduction 42, 46. Thus, in someembodiments, the disconnect mechanism 44 is provided between the gearreduction 30, 32 and the gear reduction 42, 46. Said another way, thedisconnect mechanism 44 is disposed between the gear reduction 30, 32 atthe output of the motor generator 24 and the gear reduction 42, 46connected to the layshaft 48.

The electric axle assembly 10 also comprises a second electric motorgenerator, motor generator 50. A motor shaft or output shaft 52 isoperatively coupled to the motor generator 50. The motor shaft 52 issupported by bearings 54, which are illustrated in FIG. 3. The bearings54 preferably comprise a first and second bearing.

The motor shaft 52 may be operatively connected to the gear train 28 wayof a gear 56 operatively attached to and rotating with the motor shaft52. The gear 56 and a gear 58 are engaged and rotate together.Preferably, the gear 56 and the gear 58 provide a gear reduction 56, 58.

The gear 58 is operatively attached to and rotates with an intermediateshaft 60. Preferably, the intermediate shaft 60 comprises a firstportion 62 and a second portion 64. The first portion 62 is attached tothe gear 58 and may be supported for rotation by bearings (notdepicted). The first portion 62 and the gear 58 rotate together. Thesecond portion 64 is attached to a gear 66. The second portion 64 andthe gear 66 rotate together. Preferably, the second portion 64 issupported for rotation by bearings 68, which are illustrated in FIG. 3.

As shown in both FIGS. 1 and 2, a disconnect mechanism 70 is provided inthe intermediate shaft 60 to selectively disconnect the first portion 62and the second portion 64. When the second disconnect mechanism 70 isactivated, the (rotational) power provided (transmitted) by the motorgenerator 50 is not communicated to the second portion 64 of theintermediate shaft 60. When the disconnect mechanism 70 is notactivated, the power provided by the motor generator 50 is communicatedfrom the first portion 62 to the second portion 64 of the intermediateshaft 60.

The gear 66 is engaged and rotates with the gear 46. Preferably, thegear 66 and the gear 46 provide a gear reduction 66, 46. Thus, in someembodiments, the disconnect mechanism 70 is provided between the gearreduction 56, 58 and the gear reduction 66, 46. Put another way, thedisconnect mechanism 70 is disposed between the gear reduction 56, 58 atthe output of the motor generator 50 and the gear reduction 66, 46connected to the layshaft 48.

A clutch assembly 72 is disposed about a portion of the layshaft 48. Inpreferred embodiments, the clutch assembly 72 enables the electric axle10 to exhibit two speeds. However, in some embodiments, the clutchassembly may provide engagement and disengagement between the layshaft48 and a drive gear associated with the differential 12.

Preferably, and as shown in FIGS. 1 and 2, the clutch assembly 72comprises a clutch gear assembly 74. The clutch gear assembly 74comprises a low gear 76 and a high gear 78. A clutch 80 is utilized toselectively and operatively engage the low gear 76 or the high gear 78with the layshaft 48. In some embodiments, the clutch 80 may be of thesliding collar, electromagnetic, or face variety. In other embodiments,the clutch 80 is another type of torque transferring disconnectionmechanism.

The clutch assembly 72 is engaged with a gear assembly 82. Moreparticularly, the low gear 76 is engaged and rotates with a first gear84 of the gear assembly 82 and the high gear 78 is engaged and rotateswith a second gear 86 of the gear assembly 82. Engagement of the lowgear 76 and the first gear 84 of the gear assembly 82 provides a firstgear ratio when the clutch 80 engages the low gear 76 with the layshaft48. Engagement of the high gear 78 and the second gear 86 of the gearassembly 82 provides a second gear ratio when the clutch 80 engages thehigh gear 78 with the layshaft 48.

The first gear 84 and the second gear 86 of the gear assembly 82 aremechanically coupled together via a shaft 88 or another member androtate with each other. The gear assembly 82 may be operativelyconnected to the differential 12. In some embodiments, the gear assembly82 may be mechanically coupled to the differential 12. The gear assembly82 is utilized to (transmit) transfer (rotational) power to and from thedifferential 12.

Under certain conditions, it may be desirable for the motor generator 24and the motor generator 50 to each provide power to the differential 12.However, under other conditions and to operate in the most efficientmanner, it may be preferred that the motor generator 24 or the motorgenerator 50 act as the primary driving motor with the remaining motorgenerator being at a 0 rpm (idle) condition or without providing anyadditional power needed to the differential 12. Providing a disconnectmechanism 44, 70 for each electric motor generator 24, 50 allows themotor generator 24 and the motor generator 50 to each act as the primarydriving motor or be taken to a 0 rpm condition as desired. For example,if the motor generator 24 is acting as the primary or only driving motorand a predetermined load or time has been achieved, the disconnectmechanism 44 may be activated to prevent the motor generator 24 fromcommunicating power to the differential 12 and the motor generator 50may be selected to be the primary or only driving motor. After thedisconnect mechanism 44 has been activated and the motor generator 24 isno longer communicating power to the differential 12, the motorgenerator 24 can be taken to a 0 rpm condition. In this embodiment, withthe disconnect mechanism 70 activated, the motor generator 50 can beactivated from a 0 rpm condition or another condition to permit themotor shaft 52 to achieve a desirable speed before the second motorgenerator 50 communicates power to the differential 12. Alternatively,if the motor generator 24 is acting as the primary or only driving motorand additional power is required, utilizing the disconnect mechanism 70enables the motor generator 50 to be activated and speed matching tooccur before the motor generator 50 communicates power to thedifferential 12.

Also as shown in FIGS. 1 and 2, a controller 102 is provided. In FIG. 1,the system 100 comprises a controller 102 for controllingactuation/activation/sensing/movement of the disconnect 70 and/or clutchassembly 72 (or clutch 80) via communicative couplings 108 (disconnect70) and 104 (clutch 80). In FIG. 2, the system 200 comprises acontroller 102 for controlling actuation/activation/sensing/movement ofthe disconnects 44 and 70 and/or clutch assembly 72 (or clutch 80) viacommunicative couplings 108 (disconnect 70), 202 (disconnect 44), and104 (clutch 80). Disconnects 44, 70 may comprise clutches and actuatorscommunicably coupled to the controller 102. In response to inputs fromthe disconnects 44, 70, the controller 102 may send a signal causing oneor more of the disconnects to activate (or change state). In oneembodiment, the disconnect mechanisms 44, 70 are communicably coupled toa controller 102, and the controller 102 is adapted to selectablydisconnect one of the motor generators 24, 50 via the correspondingdisconnect mechanism 44, 70 when less than a predetermined level ofpower is required by the vehicle. The predetermined level of power maybe, for example, 200 kW. In one embodiment, the disconnect 44 and thedisconnect 70 are adapted to permit engaging both the motor generator 24and the motor generator 50 at the same time so that both the motorgenerator 24 and the motor generator 50 provide power to thedifferential 12 for a predetermined duration, after which the controller102 selectably operably disconnects either the motor generator 24 or themotor generator 50 from the layshaft 48, with selection as to whichmotor generator to disconnect based on algorithms used by the controller102.

As describe in detail herein, in one embodiment, an electric axleassembly for a vehicle includes a first motor generator having a firstdisconnect mechanism disposed between a first gear reduction at theoutput of the first motor generator and a second gear reductionconnected to a layshaft, the layshaft operably coupled to a differentialvia a clutch assembly, the clutch assembly disposed on the layshaft andengaged with a gear assembly, with the gear assembly being operativelyconnected to the differential, and a second motor generator having athird gear reduction at the output of the second motor generator and afourth gear reduction connected to the layshaft, wherein the firstdisconnect mechanism is adapted to permit the first motor generator tobe selectably operably disconnected from the layshaft while the secondmotor generator remains operably connected to the layshaft.

In one aspect, the electric axle assembly further comprises a seconddisconnect mechanism disposed between the third gear reduction at theoutput of the second motor generator and the fourth gear reductionconnected to the layshaft, wherein the second disconnect mechanism isadapted to permit the second motor generator to be selectably operablydisconnected from the layshaft.

In one aspect, the first disconnect mechanism is communicably coupled toa controller, and the controller is adapted to selectably disconnect thefirst motor generator via the first disconnect mechanism when less thana predetermined level of power is required by the vehicle.

In one aspect, the first disconnect and the second disconnect areadapted to permit engaging either one of the first motor generator orthe second motor generator as a primary drive motor based on a time atload for the first motor generator and a time at load for the secondmotor generator.

In one aspect, the first disconnect and the second disconnect areadapted to permit alternating between the first motor generator and thesecond motor generator as primary drive motors during operation of thevehicle to extend the life of each driving motor.

In one aspect, the first disconnect and the second disconnect areadapted to permit engaging both the first motor generator and the secondmotor generator at the same time so that both the first motor generatorand the second motor generator provide power to the differential for apredetermined duration, after which a controller selectably operablydisconnects either the first motor generator or the second motorgenerator from the layshaft, with selection as to which motor generatorto disconnect based on algorithms used by the controller.

In one aspect, the first disconnect and the second disconnect areadapted to permit spinning up an operably disconnected motor generatorto operably match a rotational speed of the layshaft so as to operablyreconnect the formerly disconnected motor generator.

In one aspect, the first gear reduction includes a first gear thatrotates with an output shaft of the first motor generator and a secondgear that rotates with a first intermediate shaft, the second gearreduction includes a third gear that rotates with the first intermediateshaft and a fourth gear that rotates with the layshaft, the third gearreduction includes a seventh gear that rotates with a secondintermediate shaft and the fourth gear that rotates with the layshaft,and the fourth gear reduction that include a fifth gear that rotateswith an output shaft of the second motor generator and a sixth gear thatrotates with the second intermediate shaft.

In one aspect, the clutch assembly disposed on the layshaft andoperatively connected to the differential is adapted to permit operationof the electric axle assembly at one of two different rotational speeds.

In one aspect, an output shaft of the first motor generator, thelayshaft, and an output shaft of the second motor generator are in aparallel alignment with one another, the output shaft of the secondmotor generator is hollow, and at least a portion of an axle shaftoperatively coupled to the differential extends through the hollowoutput shaft of the second motor generator.

In another embodiment, an electric axle assembly in a vehicle comprises:a first motor generator; a first motor shaft operatively coupled to thefirst motor generator; a first gear reduction connected to the motorshaft; a first intermediate shaft connected to the first gear reduction;a first disconnect mechanism provided in the first intermediate shaft toselectively disconnect a first portion and a second portion of the firstintermediate shaft; a second gear reduction connected to the firstintermediate shaft; a second motor generator; a second motor shaftoperatively coupled to the second motor generator; a third gearreduction connected to the second motor shaft; a second intermediateshaft connected to the third gear reduction; a fourth gear reductionconnected to the second intermediate shaft; a layshaft connected to thesecond gear reduction and the fourth gear reduction; and a differentialoperatively connected to the layshaft.

In one aspect, the electric axle assembly further comprises a seconddisconnect mechanism provided in the second intermediate shaft toselectively disconnect a first portion and a second portion of thesecond intermediate shaft.

In one aspect, the electric axle assembly further comprises a clutchassembly disposed on the layshaft, the clutch assembly engaged with agear assembly and the gear assembly being operatively connected to thedifferential.

FIG. 3 shows an example configuration with relative positioning of thevarious components. If shown directly contacting each other, or directlycoupled, then such elements may be referred to as directly contacting ordirectly coupled, respectively, at least in one example. Similarly,elements shown contiguous or adjacent to one another may be contiguousor adjacent to each other, respectively, at least in one example. As anexample, components laying in face-sharing contact with each other maybe referred to as in face-sharing contact. As another example, elementspositioned apart from each other with only a space there-between and noother components may be referred to as such, in at least one example. Asyet another example, elements shown above/below one another, at oppositesides to one another, or to the left/right of one another may bereferred to as such, relative to one another. Further, as shown in thefigures, a topmost element or point of element may be referred to as a“top” of the component and a bottommost element or point of the elementmay be referred to as a “bottom” of the component, in at least oneexample. As used herein, top/bottom, upper/lower, above/below, may berelative to a vertical axis of the figures and used to describepositioning of elements of the figures relative to one another. As such,elements shown above other elements are positioned vertically above theother elements, in one example. As yet another example, shapes of theelements depicted within the figures may be referred to as having thoseshapes (e.g., such as being circular, straight, planar, curved, rounded,chamfered, angled, or the like). Further, elements shown intersectingone another may be referred to as intersecting elements or intersectingone another, in at least one example. Further still, an element shownwithin another element or shown outside of another element may bereferred as such, in one example.

Certain adaptations and modifications of the described embodiments canbe made. Therefore, the above discussed embodiments are considered to beillustrative and not restrictive. The present disclosure is not to belimited in scope by the specific embodiments described herein. Furtherexample embodiments may also include all of the steps, features,compositions and compounds referred to or indicated in this description,individually or collectively and any and all combinations or any two ormore of the steps or features.

Throughout this document, the use of the word “a” or “an” when used inconjunction with the term “comprising” in the claims and/or thespecification may mean “one”, but it is also consistent with the meaningof “one or more”, “at least one”, and “one or more than one”. Similarly,the word “another” may mean at least a second or more. The words“comprising” (and any form of comprising, such as “comprise’ andcomprises), “having” (and any form of having, such as “have” and “has”),“including” (and any form of including, such as “include” and“includes”) or “containing” (and any form of containing, such as“contain” and “contains”), are inclusive or open-ended and do notexclude additional, unrecited elements or process steps.

In the present specification and in the appended claims, variousterminology which is directional, geometrical and/or spatial in naturesuch as “longitudinal”, “horizontal”, “front”, “forward”, “backward”,“back”, “rear”, “upwardly”, “downwardly”, etc. is used. It is to beunderstood that such terminology is used for ease of description and ina relative sense only and is not to be taken in any way as specifying anabsolute direction or orientation.

The embodiments described herein may include one or more range of values(for example, size, displacement and field strength etc.). A range ofvalues will be understood to include all values within the range,including the values defining the range, and values adjacent to therange that lead to the same or substantially the same outcome as thevalues immediately adjacent to that value which defines the boundary tothe range. For example, a person skilled in the field will understandthat a 10% variation in upper or lower limits of a range can be totallyappropriate and is encompassed by the disclosure. More particularly, thevariation in upper or lower limits of a range will be 5% or as iscommonly recognized in the art, whichever is greater.

Throughout this specification relative language such as the words‘about’ and ‘approximately’ are used. This language seeks to incorporateat least 10% variability to the specified number or range. Thatvariability may be plus 10% or negative 10% of the particular numberspecified.

The foregoing description is considered as illustrative only of theprinciples of the invention. Further, since numerous modifications andchanges will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and processesshown and described herein. Accordingly, all suitable modifications andequivalents may be considered as falling within the scope of theinvention as defined by the claims which follow.

What is claimed is:
 1. An electric axle assembly for a vehicle,comprising: a first motor generator having a first disconnect mechanismdisposed between a first gear reduction at the output of the first motorgenerator and a second gear reduction connected to a layshaft, thelayshaft operably coupled to a differential via a clutch assembly, theclutch assembly disposed on the layshaft and engaged with a gearassembly, with the gear assembly being operatively connected to thedifferential; and a second motor generator having a third gear reductionat the output of the second motor generator and a fourth gear reductionconnected to the layshaft, wherein the first disconnect mechanism isadapted to permit the first motor generator to be selectably operablydisconnected from the layshaft while the second motor generator remainsoperably connected to the layshaft.
 2. The electric axle assembly ofclaim 1, further comprising: a second disconnect mechanism disposedbetween the third gear reduction at the output of the second motorgenerator and the fourth gear reduction connected to the layshaft,wherein the second disconnect mechanism is adapted to permit the secondmotor generator to be selectably operably disconnected from thelayshaft.
 3. The electric axle assembly of claim 1, wherein the firstdisconnect mechanism is communicably coupled to a controller, and thecontroller is adapted to selectably disconnect the first motor generatorvia the first disconnect mechanism when less than a predetermined levelof power is required by the vehicle.
 4. The electric axle assembly ofclaim 2, wherein the first disconnect and the second disconnect areadapted to permit engaging either one of the first motor generator orthe second motor generator as a primary drive motor based on a time atload for the first motor generator and a time at load for the secondmotor generator.
 5. The electric axle assembly of claim 4, wherein thefirst disconnect and the second disconnect are adapted to permitalternating between the first motor generator and the second motorgenerator as primary drive motors during operation of the vehicle toextend the life of each driving motor.
 6. The electric axle assembly ofclaim 2, wherein the first disconnect and the second disconnect areadapted to permit engaging both the first motor generator and the secondmotor generator at the same time so that both the first motor generatorand the second motor generator provide power to the differential for apredetermined duration, after which a controller selectably operablydisconnects either the first motor generator or the second motorgenerator from the layshaft, with selection as to which motor generatorto disconnect based on algorithms used by the controller.
 7. Theelectric axle assembly of claim 6, wherein the first disconnect and thesecond disconnect are adapted to permit spinning up an operablydisconnected motor generator to operably match a rotational speed of thelayshaft so as to operably reconnect the formerly disconnected motorgenerator.
 8. The electric axle assembly of claim 2, wherein the firstgear reduction includes a first gear that rotates with an output shaftof the first motor generator and a second gear that rotates with a firstintermediate shaft, the second gear reduction includes a third gear thatrotates with the first intermediate shaft and a fourth gear that rotateswith the layshaft, the third gear reduction includes a seventh gear thatrotates with a second intermediate shaft and the fourth gear thatrotates with the layshaft, and the fourth gear reduction that include afifth gear that rotates with an output shaft of the second motorgenerator and a sixth gear that rotates with the second intermediateshaft.
 9. The electric axle assembly of claim 2, wherein the clutchassembly disposed on the layshaft and operatively connected to thedifferential is adapted to permit operation of the electric axleassembly at one of two different rotational speeds.
 10. The electricaxle assembly of claim 2, wherein an output shaft of the first motorgenerator, the layshaft, and an output shaft of the second motorgenerator are in a parallel alignment with one another, the output shaftof the second motor generator is hollow, and at least a portion of anaxle shaft operatively coupled to the differential extends through thehollow output shaft of the second motor generator.
 11. An electric axleassembly in a vehicle, the electric axle assembly comprising: a firstmotor generator; a first motor shaft operatively coupled to the firstmotor generator; a first gear reduction connected to the motor shaft; afirst intermediate shaft connected to the first gear reduction; a firstdisconnect mechanism provided in the first intermediate shaft toselectively disconnect a first portion and a second portion of the firstintermediate shaft; a second gear reduction connected to the firstintermediate shaft; a second motor generator; a second motor shaftoperatively coupled to the second motor generator; a third gearreduction connected to the second motor shaft; a second intermediateshaft connected to the third gear reduction; a fourth gear reductionconnected to the second intermediate shaft; a layshaft connected to thesecond gear reduction and the fourth gear reduction; and a differentialoperatively connected to the layshaft.
 12. The electric axle assembly ofclaim 11, further comprising: a second disconnect mechanism provided inthe second intermediate shaft to selectively disconnect a first portionand a second portion of the second intermediate shaft.
 13. The electricaxle assembly of claim 11, further comprising: a clutch assemblydisposed on the layshaft, the clutch assembly engaged with a gearassembly and the gear assembly being operatively connected to thedifferential.
 14. The electric axle assembly of claim 11, wherein thefirst disconnect mechanism is communicably coupled to a controller, andthe controller is adapted to selectably disconnect the first motorgenerator via the first disconnect mechanism when less than apredetermined level of power is required by the vehicle.
 15. Theelectric axle assembly of claim 12, wherein the first disconnect and thesecond disconnect are adapted to permit engaging either one of the firstmotor generator or the second motor generator as a primary drive motorbased on a time at load for the first motor generator and a time at loadfor the second motor generator.
 16. The electric axle assembly of claim15, wherein the first disconnect and the second disconnect are adaptedto permit alternating between the first motor generator and the secondmotor generator as primary drive motors during operation of the vehicleto extend the life of each driving motor.
 17. The electric axle assemblyof claim 12, wherein the first disconnect and the second disconnect areadapted to permit engaging both the first motor generator and the secondmotor generator at the same time so that both the first motor generatorand the second motor generator provide power to the differential for apredetermined duration, after which a controller selectably operablydisconnects either the first motor generator or the second motorgenerator from the layshaft, with selection as to which motor generatorto disconnect based on algorithms used by the controller.
 18. Theelectric axle assembly of claim 13, wherein the clutch assembly disposedon the layshaft and operatively connected to the differential is adaptedto permit operation of the electric axle assembly at one of twodifferent rotational speeds.
 19. The electric axle assembly of claim 12,wherein an output shaft of the first motor generator, the layshaft, andan output shaft of the second motor generator are in a parallelalignment with one another, the output shaft of the second motorgenerator is hollow, and at least a portion of an axle shaft operativelycoupled to the differential extends through the hollow output shaft ofthe second motor generator.
 20. An electric axle assembly, comprising: afirst motor generator; a first motor shaft operatively coupled to thefirst motor generator; a first gear reduction connected to the motorshaft; a first intermediate shaft connected to the first gear reduction;a first disconnect mechanism provided in the first intermediate shaft toselectively disconnect a first portion and a second portion of the firstintermediate shaft; a second gear reduction connected to the firstintermediate shaft; a second motor generator; a second motor shaftoperatively coupled to the second motor generator; a third gearreduction connected to the second motor shaft; a second intermediateshaft connected to the third gear reduction; a second disconnectmechanism provided in the second intermediate shaft to selectivelydisconnect a first portion and a second portion of the secondintermediate shaft; a fourth gear reduction connected to the secondintermediate shaft; a layshaft connected to the second gear reductionand the fourth gear reduction; and a clutch assembly disposed on thelayshaft, the clutch assembly engaged with a gear assembly and the gearassembly being operatively connected to a differential.